30 FPS to 24 FPS for aTV

Discussion in 'Apple TV and Home Theater' started by xfiring, Apr 11, 2010.

  1. xfiring macrumors member

    Oct 10, 2009
    Title says it all, is there a way to convert 30 FPS to 24 FPS so I can get the full 1280 x 720 resolution. Otherwise I have to downgrade resolution.


    This particular files is an m2ts but mkv instructions would be fine too
  2. dynaflash macrumors 68020

    Mar 27, 2003
    Using handbrake just set the Framerate to 24 fps. Realize however that HandBrake will drop frames to get there so the video will likely stutter a bit or at least not be as smooth.
  3. fpnc macrumors 68000

    Oct 30, 2002
    San Diego, CA
    There is really no good way to do this. It's kind of like trying to put fifteen pounds of flour in a ten pound bag. You'll probably like the look of the result better by just encoding at a lower resolution and keeping the frame rate at 30fps. Thus, reduce the size to 960x540 (one half of 1080p) and keep the frame rate at the current value. Even Apple does this for their HD TV shows that come from sources that are over 24fps. For example, the HD version of the BBC TV show "Top Gear" is encoded at 960x540 because the original is shot at 25fps (the latter the European PAL rate).

    However, as dynaflash said, you can just use HandBrake or some other tool to drop frames from the existing source but that will produce a fair amount of jumpiness in the output if you have any motion at all in the original video. You might also try the freeware utility "JES Deinterlacer" as it actually produces some fairly good standards conversions (NTSC to PAL, etc.).

    Final Cut Pro and Apple's Compressor have a so-called "optical flow" mechanism that will produce new video images by interpolation between existing frames but it is VERY, VERY slow and the results aren't even that good in many cases (certainly not worth the many hours or maybe even days it takes to do the conversion).

    Lastly, is this a file that has been telecined from an original 24fps source? If so, you might be able to do an inverse telecine operation with a tool like HandBrake or JES Deinterlacer. Inverse telecine is pretty difficult also if there are any cadence breaks in the original (which is very common with any video that has been edited after it was converted from 24fps to 30fps -- which is the telecine operation itself).

    Here is an overview on telecine and inverse telecine from the HandBrake Wiki:


    If you are working from a telecined source then I'd try an inverse telecine operation in HandBrake and see if that works. If you still see some interlaced frames after the inverse telecine operation then you may want to combine the inverse telecine with a Decomb filter to remove any artifacts that were caused by cadence breaks in the original.

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